http2: keep reading during small client writes

[mcollina]

Fixes: #54874

[nodejs-github-bot]

Review requested:

• @nodejs/http2
• @nodejs/net
• @nodejs/performance

[codecov]

Codecov Report

❌ Patch coverage is 90.00000% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 89.64%. Comparing base (58a8e1d) to head (4dd0542).
⚠️ Report is 147 commits behind head on main.

Files with missing lines	Patch %	Lines
src/node_http2.cc	90.00%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #63009      +/-   ##
==========================================
- Coverage   89.69%   89.64%   -0.05%     
==========================================
  Files         706      708       +2     
  Lines      218222   220331    +2109     
  Branches    41768    42262     +494     
==========================================
+ Hits       195731   197520    +1789     
- Misses      14411    14657     +246     
- Partials     8080     8154      +74     

Files with missing lines	Coverage Δ
src/node_http2.h	91.61% <ø> (ø)
src/node_http2.cc	82.12% <90.00%> (+0.02%)	⬆️

... and 88 files with indirect coverage changes

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[pimterry]

@mcollina I've checked out the branch and the benchmark added here doesn't seem to show any real difference for me with this change. What results are you seeing? Is it that script, or some other benchmark?

[mcollina]

That's the point. I added the bench to verify this did not add a regression.

[pimterry]

This is supposed to be a performance improvement, right? The original issue is about downloads being slower under HTTP/2 than HTTP/1, I assumed the benchmark added was aiming to show that this really fixed the issue. If the one here is just guarding against regressions, can we add another here to test that this fix actually improves things to match HTTP/1?